$CaCO_3$ $\xrightarrow[excess \ H_2O]{CO_2 \ in} A$ $\xrightarrow{\Delta} B$
Identify $A$ and $B$.

Which of the following compounds is used for the preparation of quicklime?

Choose the correct statements from the following:
$(I)$ In vapour phase $BeCl_2$ exists as a chlorobridged dimer.
$(II)$ $BeSO_4$ is readily soluble in water.
$(III)$ $BeO$ is completely basic in nature.
$(IV)$ $BeCO_3$ being unstable, is kept in an atmosphere of $CO_2$.
$(V)$ $BeCO_3$ is the least soluble among all the carbonates of group $2$ elements.

$Assertion$ $(A)$: Helium and beryllium have similar outer electronic configuration $ns^2$. $Reason$ $(R)$: Both are chemically inert.

$A$ mixture of $MgCl_2$ and $MgO$ is called

Which of the following is the characteristic outer shell electronic configuration of alkaline earth metals?